In case you haven't done so by yourself already, there are several more treasures for you to find in the Shimmering Sands. The previous world map exploration (of this area) yielded five treasures in the northwest and west regions of the area. We'll now be exploring the rest (as far as possible).

East/Northeast region

On the right side of Al Mamoon's oasis are twinkling stars, indicating a forage point that contains, unsurprisingly, [SPRINGWATER].

Slightly southeast of Al Mamoon lies a large rock with some plants nearby. Search the place around the plants to find [CARROT CAKE x2].

To the east of Al Mamoon, and slightly northwest of the large rock as indicated on your world map (although there are several rocks that are not displayed on the map) you can find some twinkling stars that net a [GLOWCAP].

In the far northeast corner of the desert, search the area near the plants against the most northern rock to find [SHADOWGLASS x2].

Southeast region

Warning:
The creatures in this area are much tougher than the ones in the northern regions, so you'll want to be at least Level 15+. It's certainly possible to evade creatures, but do save your game before trying this. You can also wait with exploring this area until later.

The rock plateaus on the southeast can be accessed from their northeastern side. On the tip of the southernmost plateau,look for a [SHINBONE SHIELD].

These plateaus also give access to a more grassy ledge. The southernmost tip has a hidden [HALLOWED HABIT ROBE] for you to dig up.

The rocky plateau that branches off from the grassy ledge contains a forage point; the twinkling stars should be easily spotted. It contains a piece of [SHADOWGLASS].

On your way to Old Smoky, keep your eyes open for the first crack of lava and inspect it at its largest flowing point to find a [BURNING BLADE].

Further down the path to Old Smoky, to the far west of the path - requiring you to cast the 'Bridge' spell you can find a twinkling forage point between some trees.

Just to the northeast of Old Smoky's entrance, inspect the far end of the path to find a [PHOENIX FEATHER] near the lava stream.